Hybrid multi-fluid-particle simulations of the cosmic neutrino background

Simulation of the cosmic clustering of massive neutrinos is a daunting task, due both to their large velocity dispersion and to their weak clustering power becoming swamped by Poisson shot noise. We present a new approach, the multi-fluid hybrid-neutrino simulation, which partitions the neutrino population into multiple flows, each of which is characterised by its initial momentum and treated as a separate fluid. These fluid flows respond initially linearly to nonlinear perturbations in the cold matter, but slowest flows are later converted to a particle realisation should their clustering power exceed some threshold. After outlining the multi-fluid description of neutrinos, we study the conversion of the individual flows into particles, in order to quantify transient errors, as well as to determine a set of criteria for particle conversion. Assembling our results into a total neutrino power spectrum, we demonstrate that our multi-fluid hybrid-neutrino simulation is convergent to $<3\%$ if conversion happens at $z=19$ and agrees with more expensive simulations in the literature for neutrino fractions as high as $\Omega_\nu h^2 = 0.005$. Moreover, our hybrid-neutrino approach retains fine-grained information about the neutrinos' momentum distribution. However, the momentum resolution is currently limited by free-streaming transients excited by missing information in the neutrino particle initialisation procedure, which restricts the particle conversion to z $\gtrsim 19$ if percent-level resolution is desired.Comment: 43 pages, 19 figures; v2: 45 pages, added references, extended discussion on timing, matches version accepted by JCA

Evaluation of workplace safety performance in the Chinese petroleum industry

Reform of the Chinese petroleum industry has entered its second phase since early 1999. The productivity of the petroleum industry has been greatly improved, while the safety performance and records are not satisfactory. This paper investigates the critical factors for improving safety performance in the Chinese petroleum industry. The data used for the analysis are from a questionnaire survey administered to 480 professionals in the petroleum industry in which 143 valid responses were received. Statistical analysis techniques are used to analyze the data collected. The findings revealed that the most significant source of the safety problem is due to the combination of several reasons, including (a) violation on operating procedures, (b) obsolete facilities and equipment failures, (c) insufficient safety management system, (d) improper commands, number of casualties, and (e) production performances and operating skills. The three most essential protective methods include safety training and increasing staff's safety consciousness, cultivating safety culture, and enhancing equipment management and detecting hazards in time

Performance enhancement of permeable asphalt mixtures with recycled aggregate for concrete pavement application

The incorporation of recycled concrete aggregate (RCA) in permeable asphalt mixtures (PAMs) is an efficient method of utilizing construction demolished waste. It not only conforms to the trend of building sponge cities, but also alleviates the problem of overexploitation of natural aggregate resources. As the performance of PAM containing recycled aggregate is not comparable to natural aggregate, modification treatments and the addition of hybrid fibers are adopted as two enhancement methods to improve the performance of PAM with RAC in this study. It is found that replacing natural aggregate with recycled aggregate increases the optimum asphalt content (OAC) but decreases the residual stability. The OAC is increased by 45% when the RCA ratio is 100%, whereas applying silicone resin can give a 16.2% decrease in the OAC. Enhancing RCA with silicone resin can increase the water stability to be comparable with natural aggregate. Moreover, with modification treatment using calcium hydroxide solution, the mechanical strength of PAM is enhanced to even higher than that of natural coarse aggregate mixture alone. Improvements in both mechanical strength and water stability are also achieved by strengthening recycled aggregate with cement slurry, although the performance is less effective than using silicone resin. With the increase in the content of RCA, the permeability coefficients of PAM first decrease and then exhibit an increasing trend. The results indicate that the PAM with RCA and modification treatments can perform satisfactorily as a pavement material in practice. Applying probable modification, PAM incorporating RCA meets the criteria for use in concrete pavement applications

ASCA Observations of the Supernova Remnant VRO42.05.01

We present the results of our ASCA SIS and GIS observations of the supernova remnant VRO42.05.01. Our spectral fits indicate that the SNR is isothermal (about 8.3 X 10^6 K), consistent with our ROSAT analysis results. The absorbing column density (about 2.9 X 10^21 cm^-2) obtained from these spectral fits is much smaller than expected for the nominal distance of 5 kpc, indicating that the line of sight toward VRO42.05.01 has an unusually low gas density. The spectral resolution of ASCA allows us to determine elemental abundances for the hot X-ray emitting plasma in the bright ``wing'' component of this remnant. We find that Mg, Si, and Fe are underabundant, and attribute these low abundances to the galactic metallicity gradient and to the location of the remnant in the outer Milky Way.Comment: 13 pages, 5 figures, Late

Low-temperature synthesis of SmFeAsO0.7F0.3 wires with high transport critical current density

Ag-sheathed SmFeAsO0.7F0.3 (Sm-1111) superconducting wires were prepared by a one-step solid state reaction at temperatures as low as 850~900C, instead of commonly used temperatures of 1150~1250C. The X-ray diffraction pattern of the as-sintered samples is well indexed on the basis of tetragonal ZrCuSiAs-type structure. We characterized transport critical current density Jc of the SmFeAsO0.7F0.3 wires in increasing and subsequently decreasing fields, by a resistive four-probe method. A transport Jc as high as ~1300 A/cm^2 at 4.2 K and self field has been observed for the first time in Sm-1111 type polycrystalline superconductors. The Jc also shows a rapid depression in small applied fields as well as a magnetic-history dependence, indicating weak-linked grain boundaries. The low-temperature synthesis method can be very beneficial to fabricating the RE-1111 iron oxynictides in a convenient and safe way.Comment: 12 pages, 3 figure

The influence of anisotropic voxel caused by field of view setting on the accuracy of three-dimensional reconstruction of bone geometric models

The finite element method is playing an increasingly important role in osteoporosis screening. An accurate bone geometric model, a prerequisite for the finite element analysis, is affected by voxels. Isotropic voxel has advantages in three-dimensional reconstruction, but field of view setting usually results in anisotropic voxels. The main goal of this study was to investigate the influence of anisotropic voxel on the accuracy of three-dimensional reconstruction of bone geometric models. Sixty metatarsal bones were scanned twice with an interval of 18 months with different fields of view. We reconstructed these metatarsals and compared them. The results showed that there was no significant difference in volume, surface, length, width and height and two principal moments of inertia, indicating that anisotropic voxel caused by field of view setting has a neglectable effect on the three-dimensional reconstruction of bone geometric models, and that using finite element method based on bone geometric model reconstructed by anisotropic voxel to predict bone strength is reliable

An integrative multi-platform analysis for discovering biomarkers of osteosarcoma

<p>Abstract</p> <p>Background</p> <p>SELDI-TOF-MS (Surface Enhanced Laser Desorption/Ionization-Time of Flight-Mass Spectrometry) has become an attractive approach for cancer biomarker discovery due to its ability to resolve low mass proteins and high-throughput capability. However, the analytes from mass spectrometry are described only by their mass-to-charge ratio (<it>m</it>/<it>z</it>) values without further identification and annotation. To discover potential biomarkers for early diagnosis of osteosarcoma, we designed an integrative workflow combining data sets from both SELDI-TOF-MS and gene microarray analysis.</p> <p>Methods</p> <p>After extracting the information for potential biomarkers from SELDI data and microarray analysis, their associations were further inferred by link-test to identify biomarkers that could likely be used for diagnosis. Immuno-blot analysis was then performed to examine whether the expression of the putative biomarkers were indeed altered in serum from patients with osteosarcoma.</p> <p>Results</p> <p>Six differentially expressed protein peaks with strong statistical significances were detected by SELDI-TOF-MS. Four of the proteins were up-regulated and two of them were down-regulated. Microarray analysis showed that, compared with an osteoblastic cell line, the expression of 653 genes was changed more than 2 folds in three osteosarcoma cell lines. While expression of 310 genes was increased, expression of the other 343 genes was decreased. The two sets of biomarkers candidates were combined by the link-test statistics, indicating that 13 genes were potential biomarkers for early diagnosis of osteosarcoma. Among these genes, cytochrome c1 (CYC-1) was selected for further experimental validation.</p> <p>Conclusion</p> <p>Link-test on datasets from both SELDI-TOF-MS and microarray high-throughput analysis can accelerate the identification of tumor biomarkers. The result confirmed that CYC-1 may be a promising biomarker for early diagnosis of osteosarcoma.</p